An interesting (to me, at least) "Polkstand" experience

mhardy6647

Thanks to a karmic activity by PF member Rev. Hayes, I am the proud possessor of a pair of his DIY re-constructions of the original Polk Audio Monitor Series loudspeaker "Polkstand" speaker stands. These, it may be recalled, were designed to "lift and separate" (not unlike the Playtex Living Bra) Monitor Series Model 7 and 10 speakers to improve LF smoothness and definition, and also to "time align" :-) the drivers (or, at least, to point the tweeter and midbass driver at the listening position). These simple stands were quite effective; the Model 7 and 10 loudspeakers (at least to me) sound considerably better sitting on 'em than sitting on the floor.



Fast forward to 2011. As it happens, I have become the somewhat bewildered owner of a hand-me-down pair of Radio Shack "Optimus" branded Mach Two speakers (?!). Some of you may remember the Mach One (which, with a little help from the Klipsch Heresy, set back the cause of horn-loaded loudspeakers for a generation). Radio Shack, in their zeal to provide loud sound at high prices, later came out with the "new and improved" Mach Two, with a different (in fact, better) tweeter and a cone rather than horn MR... and a larger, ported enclosure (vs. the Mach One's too small, sealed, high Qtc box). Now, folks like you and me probably would never have bought a pair of these... but... how could one turn down a free pair?

See page 18 of http://www.radioshackcatalogs.com/catalogs/1991/ for the R/S blurb on these from the first year they were branded "Optimus" instead of "Realistic".

The Mach Twos are fairly sensitive (94 dB/1W@1m according to R/S), so I have tried them on a couple of tube amplifiers (PP EL84 and SE 2A3) with dismal results. Last night, in a fit of "what the heck?", I dragged the Mach Twos and an arbitrarily chosen soiled state amp (actually a Sansui ss receiver of ca. 40 to 50 wpc) upstairs. I also decided it might be interesting to stick the Mach Twos on the good Reverend's Polkstands (they're roughly the size of Monitor 10s, a little bigger actually).





Well, I wasn't really expecting too much - put the latest Wailin' Jennys CD ([Bright Morning Stars, http://www.thewailinjennys.com/)... and I was most pleasantly surprised. The speakers were smooth; the midbass was not humped up, the HF was clean and crisp. LF was decent although the bottom bottom was AWOL; an hour or more of listening (albeit to good-sounding program material) was nonfatiguing.

Now, there were a lot of variables. Ca. 10x (10 dB) power increase; high-DF SS amp in place of low-DF SE tube amp (with no global negative feedback)... and those Polkstands.

I think most of the magic was in the Polkstands :-)

But I was pretty surprised, let me tell you...

rromeo923

I would be interested in some of those stands. They look nice!

cnh

That's really interesting. I remember those RS speakers well...especially the 15" cones which we used to imagine as big party-blasters. And I'm not surprised that they sound 'better' on stands with an SS amp?

It would be fascinating to hear how that set up sounds.

Enjoy!

cnh

mhardy6647

I'm always surprised when something sounds better driven by a soiled state amplifier ;-)

FYI and FWIW, this is the rather odd Sansui Rx that I used in that little experiment... I don't remember these from "back in the day", so I snagged this one (TA-500) when it became available from one of the AK luminaries some time back. I can now say that it's a pretty respectable sounding piece of hardware.

halo71

Very nice looking stands.

dorokusai

Mark - Is the Rev Hayes selling them or was it just a one off? I'd like to get them in the Polk accesories forum along with TLF's rings and Gimpods' xover boards if so.

mhardy6647

It was, I believe, a one-off "Karma" thing. They're quite nice, though.
http://www.polkaudio.com/forums/showthread.php?t=106469&highlight=stands

(interestingly his thread references yours: http://www.polkaudio.com/forums/showthread.php?t=24335)

dorokusai

He contacted me offline to clarify some stuff if I recall. He's a very nice guy.

WOW, I posted that in 2004. I feel old and still helpful.

mhardy6647

dorokusai wrote: »

He contacted me offline to clarify some stuff if I recall. He's a very nice guy.

WOW, I posted that in 2004. I feel old and still helpful.

I'm sure that I am both older and less helpful than you are... :-P

soundfreak1

Very nice

mhardy6647

DSkip wrote: »

So out of curiosity, are the Mach One's any good? I'll probably be snagging my grandfather's pair (along with the packaged Realistic stereo receiver) after we close on the house.

Mach Ones, you say?
Well, I'm not a big fan, but there are people who like them. Their most salient flaw is a 15" woofer in a too small sealed box - this is a recipe for high Qtc thumpa-thumpa peaked midbass - which was oh-so-popular in the latter half of the 1970s (in some circles). The titular Mach Twos of this thread, to their credit, have a different woofer in a considerably larger, ported box - and although they don't go very low, they aren't objectionably thumpy, either.

OldmanSRS

DSkip wrote: »

So out of curiosity, are the Mach One's any good? I'll probably be snagging my grandfather's pair (along with the packaged Realistic stereo receiver) after we close on the house.

Grandfather? Now that makes me feel old. I had a pair in 1977 and the best RS receiver to drive them. Was working full time in a decent job and spent a months salary on the setup.

Good? Well they could move a room with the disco energy. Their main attribute was efficiency and thump. Good dance speakers then and now. Don't have them anymore and in 1988, spent several months salary (took out a loan) to buy the SRS1.2, a Carver 1.0t, an Adcom preamp, and a Sony CD player. Back then it was hard to find CD's in the record store.

Still have all that equipment, some in use and some stored.

OldmanSRS

I would keep them as-is and use them for parties inside or outside. I was only 20, not 50's when I got mine so I don't feel quite as old now

Cayuga

I have a pair of 10's and would love to find some stands. Knock-offs or originals.

mhardy6647

Cayuga wrote: »

I have a pair of 10's and would love to find some stands. Knock-offs or originals.

you may 'roll your own'...
http://www.polkaudio.com/forums/showthread.php?t=24335

George Grand

mhardy6647 wrote: »

Mach Ones, you say?
Well, I'm not a big fan, but there are people who like them. Their most salient flaw is a 15" woofer in a too small sealed box - this is a recipe for high Qtc thumpa-thumpa peaked midbass - which was oh-so-popular in the latter half of the 1970s (in some circles). The titular Mach Twos of this thread, to their credit, have a different woofer in a considerably larger, ported box - and although they don't go very low, they aren't objectionably thumpy, either.

A guy on AK needed some Mach One woofs re-foamed, and he lived near here. I told him the next time I was going down to my re-foam guy, I would take him and his woofers with me, so he'd know where to go from then on in. All the way down there he played with his 15" Mach One woofers, and the 8" Ohm woofers I was bringing down. I know the thought "Why do my 15" woofers weigh about one third of what his 8" woofers weigh?" definitely went through his mind. His mouth didn't mention it, but his face did.

It wasn't too far down the road (calendar road) that I believe he gave up on those Rat Shacks, and he stopped by to buy a pair of AR-98LS 12" three-ways off me. Not long after he paid to get the Mach One's re-foamed. Money pissed away.

mhardy6647

we'll bring 'em all around - one pair of speakers at a time...

Big Dawg

George Grand wrote: »

A guy on AK needed some Mach One woofs re-foamed, and he lived near here. I told him the next time I was going down to my re-foam guy, I would take him and his woofers with me, so he'd know where to go from then on in. All the way down there he played with his 15" Mach One woofers, and the 8" Ohm woofers I was bringing down. I know the thought "Why do my 15" woofers weigh about one third of what his 8" woofers weigh?" definitely went through his mind. His mouth didn't mention it, but his face did.

It wasn't too far down the road (calendar road) that I believe he gave up on those Rat Shacks, and he stopped by to buy a pair of AR-98LS 12" three-ways off me. Not long after he paid to get the Mach One's re-foamed. Money pissed away.

Who do you use for re-foam? Miller Sound?

agfrost

mhardy6647 wrote: »

I'm always surprised when something sounds better driven by a soiled state amplifier ;-)

FYI and FWIW, this is the rather odd Sansui Rx that I used in that little experiment... I don't remember these from "back in the day", so I snagged this one (TA-500) when it became available from one of the AK luminaries some time back. I can now say that it's a pretty respectable sounding piece of hardware.

I gots me one of those! Love that ivory-and-black Sansui look. Sounds pretty nice, I agree.

dorokusai

Agreed, it's sharp looking color contrast. I like that series of Sansui as well.

treitz3

Serious question here folks, does anybody know what angle the speakers were tilted back with these stands?

dorokusai

It's somewhere in my thread on building them....6 degrees keeps popping into my head. This also varied +/- a degree depending on what version of Polkstand you have. I believe it varies between 4-6 degrees, any of which would be fine for the sake of heated debate.

mhardy6647

we could do some calculations involving frequency, the speed of sound, the barometric pressure, the % relative humidity of the air... and possibly Planck's Constant, to discern the optimal tiltback :-)

goosonano

Yes, people get that experience by being employed in various entry level flying positions like.

Jstas

dorokusai wrote: »

It's somewhere in my thread on building them....6 degrees keeps popping into my head. This also varied +/- a degree depending on what version of Polkstand you have. I believe it varies between 4-6 degrees, any of which would be fine for the sake of heated debate.

It's 4 to 6 degrees. Height matters as well because a taller stand needs less pitch because the cross axis of the vertical and horizontal planes are nearer to the listening position. The tilt gives two benefits, better directional response because the speaker is aimed at your face instead of the walls behind you on either side of your head and a type of "poor man's" time alignment for the voice coils in the driver array.

I went through all of this when multiple people asked if my father was interested in building stands for them and only one person followed through. I have plans worked out to build exact duplicates of the original Polk Audio stands. The plans were modified to also allow for a removable top to the hollow upright on the base to fill with shot or sand or what ever. The plans allow for a pitch between 4 and 6 degrees, any height that you'd like to have and the bases are thick enough to be tapped for spikes. Construction is done in a way that any material from solid wood to plywood to garbage MDF can be used.

treitz3

Eh, I was just wondering because it seems that the Amazings were at about a 2-3 degree angle and my Tylers sound their best when at the same angle. I have no desire to get all scientific and mathematical about it because at the end of the day I would trust my ears no matter what. I was just curious is all. Thanks.

Jstas

treitz3 wrote: »

Eh, I was just wondering because it seems that the Amazings were at about a 2-3 degree angle and my Tylers sound their best when at the same angle. I have no desire to get all scientific and mathematical about it because at the end of the day I would trust my ears no matter what. I was just curious is all. Thanks.

It's not scientific. The various Monitors and RTA speakers that had stands have varying heights and the pitch varies with the height. If you want to replicate it, either grab the plans that are posted somewhere on this site or find someone who has stands from the model speaker you have and get them to measure things.

That's what I did because the plans I had gave a varying degree. If you have a 6 degree pitch but a 12 inch tall stand, a Monitor 10 will be point at the ceiling above your head. Kinda defeats the purpose of the pitch. But, IIRC, monitor 10's were taller than, say, Monitor 7's so they didn't need quite as much pitch. So a Monitor 10 stand would be about 4 degrees while a physically shorter Monitor 7 would have a lower overall driver placement and require a steeper pitch to direct the sound at your ears. So a monitor 7 stand would have a 6 degree pitch.

Joe08867

Jstas wrote: »

It's not scientific. The various Monitors and RTA speakers that had stands have varying heights and the pitch varies with the height. If you want to replicate it, either grab the plans that are posted somewhere on this site or find someone who has stands from the model speaker you have and get them to measure things.

That's what I did because the plans I had gave a varying degree. If you have a 6 degree pitch but a 12 inch tall stand, a Monitor 10 will be point at the ceiling above your head. Kinda defeats the purpose of the pitch. But, IIRC, monitor 10's were taller than, say, Monitor 7's so they didn't need quite as much pitch. So a Monitor 10 stand would be about 4 degrees while a physically shorter Monitor 7 would have a lower overall driver placement and require a steeper pitch to direct the sound at your ears. So a monitor 7 stand would have a 4 degree pitch.

Well that about sums that up Jstas. Any questions????

I didn't think so......

Jstas

Joe08867 wrote: »

Well that about sums that up Jstas. Any questions????

I didn't think so......

Yeah, I edited that last part. It should be 6 degrees for the Monitor 7 stand, not 4. I goofed.

TennMan

Jstas wrote: »

It's not scientific. The various Monitors and RTA speakers that had stands have varying heights and the pitch varies with the height. If you want to replicate it, either grab the plans that are posted somewhere on this site or find someone who has stands from the model speaker you have and get them to measure things.

That's what I did because the plans I had gave a varying degree. If you have a 6 degree pitch but a 12 inch tall stand, a Monitor 10 will be point at the ceiling above your head. Kinda defeats the purpose of the pitch. But, IIRC, monitor 10's were taller than, say, Monitor 7's so they didn't need quite as much pitch. So a Monitor 10 stand would be about 4 degrees while a physically shorter Monitor 7 would have a lower overall driver placement and require a steeper pitch to direct the sound at your ears. So a monitor 7 stand would have a 6 degree pitch.

IF the intent is to direct the sound at your ears, wouldn't the distance from the speakers to your ears need to be taken into consideration? I don't see anything mentioned about that in your reasoning for tilting the speakers.

Jstas

TennMan wrote: »

IF the intent is to direct the sound at your ears, wouldn't the distance from the speakers to your ears need to be taken into consideration? I don't see anything mentioned about that in your reasoning for tilting the speakers.

You'll need to talk to the Polk Engineers about that. I'm not going to debate the merits of time alignment methods with you. I didn't mention it because I don't care. The questions from the posters were about the degree of pitch for the original stands. Considering I have duplicated these stands for at least one member here and quite successfully, I can speak to what the proper degree of pitch is for the original stand. Stay on topic and if you can't take your concerns to PM where I can ignore you more effectively.